Distance learning, or virtual classes, via TV and/or the Internet, has been used as an alternative to live classroom education in schools. Virtual classes provide great flexibility, allowing participants of the virtual class to attend a class from their homes or other convenient locations without limiting the total number of students in the class. The class may be pre-recorded and played at different times to accommodate students with conflicting schedules. In the traditional distance learning technology, however, only limited interactions among the students and the teacher are possible. As a result, learning in virtual classes may be less effective than in live classroom settings.